1. Field of the Invention
The present invention relates to an elevator control apparatus utilizing a power storage unit and, more particularly, to an elevator control apparatus capable of uniformly charging the power storage unit.
2. Description of the Related Art
A conventional elevator control apparatus will be described with reference to an accompanying drawing. FIG. 16 shows a construction of a conventional elevator control apparatus disclosed in, for example, Japanese Unexamined Patent Application Publication No. 61-267675.
The conventional elevator control apparatus shown in FIG. 16 includes a commercial three-phase AC power source 1, a converter 2 composed of diodes or the like, a capacitor 3, an inverter 4, a motor 5, such as an induction motor, a hoisting machine 6, an elevator car 7, a counterweight 8, and a rope 9. The control apparatus further includes a power storage unit 10 composed of a battery, a charging and discharging (hereinafter referred to as xe2x80x9ccharge/discharge) circuit 11 composed of a DC/DC converter or the like for performing power conversion in both directions between two different DC voltages of a battery voltage and an inverter input voltage, a charge/discharge control circuit 12 for controlling the charge/discharge circuit 11 as to the direction of power conversion and battery currents, a voltage detector 13, a voltage detector 14 for the power source 1, a battery current detector 15, and a battery charge amount detector 16.
An operation of the aforesaid conventional elevator control apparatus will now be described with reference to the drawing.
If the AC power source 1 incurs a power failure, power is supplied from the power storage unit 10 to an input section of the inverter 4 by the charge/discharge circuit 11 so as to drive the motor 5 by the inverter 4 thereby to land an elevator.
In normal operation, if an inverter input voltage drops while an elevator is accelerating, then power is supplied from the power storage unit 10 to the input section of the inverter 4 by the charge/discharge circuit 11 so as to restrain a voltage drop in the input section of the inverter 4.
Conversely, if the inverter input voltage rises due to regenerative electric power from the motor 5 while an elevator is being braked, then power is supplied from the input section of the inverter 4 to the power storage unit 10 by the charge/discharge circuit 11 so as to charge the power storage unit 10. When a charge amount of the power storage unit, 10 becomes low, power is supplied from the input section of the inverter 4 to the power storage unit 10 by the charge/discharge circuit 11 to charge the power storage unit, 10.
The conventional elevator control apparatus described above employs a battery as the power storage unit, and the state of charge of the battery cannot be always maintained at 100% due to repeated charging and discharging of the battery according to an operation state of an elevator, or for ensuring an allowance for charging regenerative electric power. As a result, an inactive material is generated in the battery, presenting a problem in that an apparent charging capacity of the battery decreases with a consequent shortened life of the battery.
The present invention has been made with a view toward solving the problems mentioned above, and it is an object of the present invention to provide an elevator control apparatus capable of restraining a drop in charging capacity of a battery and deterioration of the battery, and also capable of conducting control to ensure economical charging and discharging of the battery by minimizing waste of electric power.
To this end, according to one aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge control circuit that issues a drive signal such that an amount of discharge from the power storage unit increases within a range of power that can be discharged when an elevator is driven immediately following completion of uniform charging; and a charge/discharge circuit for carrying out discharge from the power storage unit in accordance with the drive signal.
In a preferred form of the elevator control apparatus in accordance with the present invention, the charge/discharge control circuit sets the discharge amount of the power storage unit to a preset maximum value until a preset reference value of a charge state is reached, immediately following the completion of the uniform charging.
According to another aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge control circuit that issues a drive signal for controlling charge current to a predetermined constant current value when charging the power storage unit with regenerative electric power if a charge state of the power storage unit indicates a predetermined value or more immediately following completion of uniform charging; and a charge/discharge circuit for charging the power storage unit with the regenerative electric power in accordance with the drive signal.
According to yet another aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge control circuit that issues a drive signal for starting uniform charging of the power storage unit at a preset time when the elevator is less frequently used; and a charge/discharge circuit for starting the uniform charging of the power storage unit in accordance with the drive signal.
In another preferred form of the elevator control apparatus of the present invention, the charge/discharge control circuit issues a drive signal for starting uniform charging of the power storage unit at a preset time in the nighttime.
According to still another aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge control circuit that issues a drive signal for performing uniform charging of the power storage unit during a halt of the elevator based on information regarding an elevator operation supplied by the controller, measures a time of the uniform charging by a timer, issues a drive signal for interrupting the uniform charging and stopping the timer when the elevator is being started, totalizes an amount of discharge from the power storage unit up to that moment, and, when the elevator is stopped again, issues a drive signal for correcting a charging time corresponding to the totalized amount of discharge based on the uniform charging time measured by the timer before restarting the uniform charging, and also restarts measurement of uniform charging time by the timer; and a charge/discharge circuit for starting or interrupting uniform charging of the power storage unit in accordance with the drive signals.
According to a further aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge control circuit that issues a drive signal for starting uniform charging of the power storage unit when a preset two or more days have passed from a day when previous uniform charging was started; and a charge/discharge circuit that starts uniform charging of the power storage unit in accordance with the drive signal.
In a preferred form of the elevator control apparatus according to the present invention, the charge/discharge control circuit issues a drive signal for starting uniform charging of the power storage unit on a preset day of the week when the elevator is used less frequently.
According to another aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge circuit for charging the power storage unit and causing the power storage unit to discharge according to a drive signal; and a charge/discharge control circuit that controls a charge state of the power storage unit and outputs a drive signal for charging the power storage unit or causing the power storage unit to discharge, and changes a set application range of the charge state of the power storage unit based on an open circuit voltage of the power storage unit immediately following completion of uniform charge.
According to a further aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge circuit for charging the power storage unit and causing the power storage unit to discharge according to a drive signal; and a charge/discharge control circuit that controls a charge state of the power storage unit and outputs a drive signal for charging the power storage unit or causing the power storage unit to discharge,.and corrects the charge state immediately following completion of uniform charge of the power storage unit.
In a preferred form of the elevator control apparatus according to the present invention, the charge/discharge control circuit sets the charge state of the power storage unit immediately following completion of uniform charging of the power storage unit to 100%.
In another preferred form of the elevator control apparatus according to the present invention, the charge/discharge control circuit decides a value of a fully charged state of the power storage unit based on an open circuit voltage of the power storage unit immediately following completion of uniform charge of the power storage unit.
According to another aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge circuit for charging the power storage unit and causing the power storage unit to discharge according to a drive signal; and a charge/discharge control circuit that controls a charge state of the power storage unit and outputs a drive signal for charging the power storage unit or causing the power storage unit to discharge, performs uniform charging of the power storage unit at constant current in a plurality of steps, and if a charge state of the power storage unit exceeds 100%, maintains the charge state of the power storage unit at 100% until discharge from the power storage unit is carried out, even when more than 100% charging is performed.
According to another aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge circuit for charging the power storage unit and causing the power storage unit to discharge according to a drive signal; and a charge/discharge control circuit that controls a charge state of the power storage unit and outputs a drive signal for charging the power storage unit or causing the power storage unit to discharge, and calculates a current value that is uniquely determined relative to a value obtained by detecting a charge current supplied to the power storage unit, a DC bus voltage output by the converter, and a voltage of the power storage unit, and a charge current command value so as to provide a command value, and PWM-controls the charge/discharge circuit thereby to control the charge current supplied to the power storage unit by using the command value.